/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 *
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 *
 */
package javax.swing.text;

import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;

/**
 * Extends the multi-line plain text view to be suitable
 * for a single-line editor view.  If the view is
 * allocated extra space, the field must adjust for it.
 * If the hosting component is a JTextField, this view
 * will manage the ranges of the associated BoundedRangeModel
 * and will adjust the horizontal allocation to match the
 * current visibility settings of the JTextField.
 *
 * @author Timothy Prinzing
 * @see View
 */
public class FieldView extends PlainView {

  /**
   * Constructs a new FieldView wrapped on an element.
   *
   * @param elem the element
   */
  public FieldView(Element elem) {
    super(elem);
  }

  /**
   * Fetches the font metrics associated with the component hosting
   * this view.
   *
   * @return the metrics
   */
  protected FontMetrics getFontMetrics() {
    Component c = getContainer();
    return c.getFontMetrics(c.getFont());
  }

  /**
   * Adjusts the allocation given to the view
   * to be a suitable allocation for a text field.
   * If the view has been allocated more than the
   * preferred span vertically, the allocation is
   * changed to be centered vertically.  Horizontally
   * the view is adjusted according to the horizontal
   * alignment property set on the associated JTextField
   * (if that is the type of the hosting component).
   *
   * @param a the allocation given to the view, which may need to be adjusted.
   * @return the allocation that the superclass should use.
   */
  protected Shape adjustAllocation(Shape a) {
    if (a != null) {
      Rectangle bounds = a.getBounds();
      int vspan = (int) getPreferredSpan(Y_AXIS);
      int hspan = (int) getPreferredSpan(X_AXIS);
      if (bounds.height != vspan) {
        int slop = bounds.height - vspan;
        bounds.y += slop / 2;
        bounds.height -= slop;
      }

      // horizontal adjustments
      Component c = getContainer();
      if (c instanceof JTextField) {
        JTextField field = (JTextField) c;
        BoundedRangeModel vis = field.getHorizontalVisibility();
        int max = Math.max(hspan, bounds.width);
        int value = vis.getValue();
        int extent = Math.min(max, bounds.width - 1);
        if ((value + extent) > max) {
          value = max - extent;
        }
        vis.setRangeProperties(value, extent, vis.getMinimum(),
            max, false);
        if (hspan < bounds.width) {
          // horizontally align the interior
          int slop = bounds.width - 1 - hspan;

          int align = ((JTextField) c).getHorizontalAlignment();
          if (Utilities.isLeftToRight(c)) {
            if (align == LEADING) {
              align = LEFT;
            } else if (align == TRAILING) {
              align = RIGHT;
            }
          } else {
            if (align == LEADING) {
              align = RIGHT;
            } else if (align == TRAILING) {
              align = LEFT;
            }
          }

          switch (align) {
            case SwingConstants.CENTER:
              bounds.x += slop / 2;
              bounds.width -= slop;
              break;
            case SwingConstants.RIGHT:
              bounds.x += slop;
              bounds.width -= slop;
              break;
          }
        } else {
          // adjust the allocation to match the bounded range.
          bounds.width = hspan;
          bounds.x -= vis.getValue();
        }
      }
      return bounds;
    }
    return null;
  }

  /**
   * Update the visibility model with the associated JTextField
   * (if there is one) to reflect the current visibility as a
   * result of changes to the document model.  The bounded
   * range properties are updated.  If the view hasn't yet been
   * shown the extent will be zero and we just set it to be full
   * until determined otherwise.
   */
  void updateVisibilityModel() {
    Component c = getContainer();
    if (c instanceof JTextField) {
      JTextField field = (JTextField) c;
      BoundedRangeModel vis = field.getHorizontalVisibility();
      int hspan = (int) getPreferredSpan(X_AXIS);
      int extent = vis.getExtent();
      int maximum = Math.max(hspan, extent);
      extent = (extent == 0) ? maximum : extent;
      int value = maximum - extent;
      int oldValue = vis.getValue();
      if ((oldValue + extent) > maximum) {
        oldValue = maximum - extent;
      }
      value = Math.max(0, Math.min(value, oldValue));
      vis.setRangeProperties(value, extent, 0, maximum, false);
    }
  }

  // --- View methods -------------------------------------------

  /**
   * Renders using the given rendering surface and area on that surface.
   * The view may need to do layout and create child views to enable
   * itself to render into the given allocation.
   *
   * @param g the rendering surface to use
   * @param a the allocated region to render into
   * @see View#paint
   */
  public void paint(Graphics g, Shape a) {
    Rectangle r = (Rectangle) a;
    g.clipRect(r.x, r.y, r.width, r.height);
    super.paint(g, a);
  }

  /**
   * Adjusts <code>a</code> based on the visible region and returns it.
   */
  Shape adjustPaintRegion(Shape a) {
    return adjustAllocation(a);
  }

  /**
   * Determines the preferred span for this view along an
   * axis.
   *
   * @param axis may be either View.X_AXIS or View.Y_AXIS
   * @return the span the view would like to be rendered into &gt;= 0. Typically the view is told to
   * render into the span that is returned, although there is no guarantee. The parent may choose to
   * resize or break the view.
   */
  public float getPreferredSpan(int axis) {
    switch (axis) {
      case View.X_AXIS:
        Segment buff = SegmentCache.getSharedSegment();
        Document doc = getDocument();
        int width;
        try {
          FontMetrics fm = getFontMetrics();
          doc.getText(0, doc.getLength(), buff);
          width = Utilities.getTabbedTextWidth(buff, fm, 0, this, 0);
          if (buff.count > 0) {
            Component c = getContainer();
            firstLineOffset = sun.swing.SwingUtilities2.
                getLeftSideBearing((c instanceof JComponent) ?
                        (JComponent) c : null, fm,
                    buff.array[buff.offset]);
            firstLineOffset = Math.max(0, -firstLineOffset);
          } else {
            firstLineOffset = 0;
          }
        } catch (BadLocationException bl) {
          width = 0;
        }
        SegmentCache.releaseSharedSegment(buff);
        return width + firstLineOffset;
      default:
        return super.getPreferredSpan(axis);
    }
  }

  /**
   * Determines the resizability of the view along the
   * given axis.  A value of 0 or less is not resizable.
   *
   * @param axis View.X_AXIS or View.Y_AXIS
   * @return the weight -&gt; 1 for View.X_AXIS, else 0
   */
  public int getResizeWeight(int axis) {
    if (axis == View.X_AXIS) {
      return 1;
    }
    return 0;
  }

  /**
   * Provides a mapping from the document model coordinate space
   * to the coordinate space of the view mapped to it.
   *
   * @param pos the position to convert &gt;= 0
   * @param a the allocated region to render into
   * @return the bounding box of the given position
   * @throws BadLocationException if the given position does not represent a valid location in the
   * associated document
   * @see View#modelToView
   */
  public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException {
    return super.modelToView(pos, adjustAllocation(a), b);
  }

  /**
   * Provides a mapping from the view coordinate space to the logical
   * coordinate space of the model.
   *
   * @param fx the X coordinate &gt;= 0.0f
   * @param fy the Y coordinate &gt;= 0.0f
   * @param a the allocated region to render into
   * @return the location within the model that best represents the given point in the view
   * @see View#viewToModel
   */
  public int viewToModel(float fx, float fy, Shape a, Position.Bias[] bias) {
    return super.viewToModel(fx, fy, adjustAllocation(a), bias);
  }

  /**
   * Gives notification that something was inserted into the document
   * in a location that this view is responsible for.
   *
   * @param changes the change information from the associated document
   * @param a the current allocation of the view
   * @param f the factory to use to rebuild if the view has children
   * @see View#insertUpdate
   */
  public void insertUpdate(DocumentEvent changes, Shape a, ViewFactory f) {
    super.insertUpdate(changes, adjustAllocation(a), f);
    updateVisibilityModel();
  }

  /**
   * Gives notification that something was removed from the document
   * in a location that this view is responsible for.
   *
   * @param changes the change information from the associated document
   * @param a the current allocation of the view
   * @param f the factory to use to rebuild if the view has children
   * @see View#removeUpdate
   */
  public void removeUpdate(DocumentEvent changes, Shape a, ViewFactory f) {
    super.removeUpdate(changes, adjustAllocation(a), f);
    updateVisibilityModel();
  }

}
